Accelerating Network Communications

ABSTRACT

There is disclosed a method for accelerating network communications. The method may be implemented on a server computer or other computing device. The method may exist as a software program and may be stored on a storage medium. The method may include receiving a request, forwarding the request to a server, receiving a response from the server, and reviewing the response to determine whether the response includes a native expiration. When the response does not include the native expiration, a calculated expiration for the response may be computed. The calculated expiration may be inserted into the response creating an amended response. The amended response may be forwarded to the client. When the response includes the native expiration, the response may be forwarded to the client. The amended response may be stored and provided to other requesters.

RELATED APPLICATION INFORMATION

This application is a Continuation of application Ser. No. 10/699,439filed Oct. 30, 2003 entitled “Accelerating Network Communications” whichis incorporated herein by reference.

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. This patent document may showand/or describe matter which is or may become trade dress of the owner.The copyright and trade dress owner has no objection to the facsimilereproduction by any one of the patent disclosure as it appears in thePatent and Trademark Office patent files or records, but otherwisereserves all copyright and trade dress rights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is related to network communications.

2. Description of Related Art

The Internet is ubiquitous in modern society. Many persons access theInternet by using a dial-up telephone connection to an Internet accessprovider (IAP). A person who uses an IAP subscribes to and pays a fee toaccess the Internet through the IAP. The IAP may provide additionalservices to a subscriber. In general, the IAP receives subscriberrequests for information and obtains the requested information from asource on the Internet. The information requested may be an Internet webpage.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an environment in accordance with theinvention.

FIG. 2 is a block diagram of a second environment in accordance with theinvention.

FIG. 3 is a block diagram of a software architecture in accordance withthe invention.

FIG. 4 is a flow chart of a method in accordance with the invention.

FIG. 5 is a flow chart of a second method in accordance with theinvention.

FIG. 6 is a flow chart of a method to compute the expiration of aresponse in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

Throughout this description, the embodiments and examples shown shouldbe considered as exemplars, rather than limitations on the apparatus andmethods of the present invention.

A System

FIG. 1 is a block diagram of a first environment in accordance with theinvention. To access a network 140, a person may subscribe to a networkaccess provider (NAP). Such a person is referred to herein as asubscriber. A NAP is a company that provides a subscriber access to anetwork 140, such as the Internet. A person who uses a NAP typicallysubscribes to and pays a fee to access the network 140 through the NAP.Typically, the subscriber uses a client computer 110 and establishes aconnection 114 with a server computer 120 of the NAP. The servercomputer 120 provides access to the network 140. The connection 114 maybe a persistent connection.

The server 120 may be a single server as shown, or may be a group of twoor more servers, and may include network devices such as routers,gateways, switches and others. The client computer 110 may be coupledfor communication with a server computer 120 which provides the clientcomputer 110 access to the network 140, such as, for example, theInternet. The connection 114 between client computer 110 and server 120may be wired or wireless, may be a dial-up telephone connection, and maybe a broadband connection such as, for example, a digital subscriberline (DSL), cable, integrated services digital network (ISDN), andothers. The connection 114 may include intermediate nodes and devices.These intermediate nodes may be modems, routers, switches, gateways,servers and others. Similarly, intermediate nodes and devices may existbetween the server 120 and the network 140.

Information from devices 130 may be accessed by the subscriber vianetwork 140. The client computer 110 may access and otherwise obtaininformation from devices 130 by establishing a connection with server120. Server 120 provides client computer 110 access to network 140 and amyriad of devices 130 by communicating through network 140.

The techniques described herein may be implemented to increase thenetwork communications throughput to a computing device and/or through anetwork server, resulting in accelerated network communications.

Client computer 110 may be a personal computer, as shown, or othercomputing device. Devices 130 may be web servers or other computingdevices. A computing device as used herein refers to any device with aprocessor and memory that may execute instructions including, but notlimited to, personal computers, server computers, computing tablets, settop boxes, video game systems, personal video recorders, telephones,personal digital assistants (PDAs), portable computers, and laptopcomputers. Computing devices may also include network devices such asrouters, gateways, switches and others.

The client computer 110 or other computing devices may have a networkinterface card (NIC), wireless access device, or modem included thereinor coupled thereto to allow for network communications such as, forexample, communication with server 120 and over network 140 with devices130.

The server computer 120 may be any server computer. The server computer120 may include software, firmware, and/or hardware for providing thefunctionality and features of the invention. The invention may beembodied in whole or in part in software which operates on the servercomputer 120 and may be in the form of an application program, one ormore subroutines, one or more plug-in modules, an operating systemcomponent or service, and others. The hardware and software of theinvention and its functions may be distributed such that somefunctionality is performed by the server computer 120, and otherfunctionality is performed by other computing devices which may belocally or remotely accessible.

The techniques discussed herein are described with regard to softwarewhich may be stored on, transferred from and/or executed from a storagemedium in a storage device included with or otherwise coupled orattached to a computing device such as server 120. These storage mediainclude, for example, magnetic media such as hard disks, floppy disksand tape; optical media such as compact disks (CD-ROM and CD-RW) anddigital versatile disks (DVD and DVD±RW); flash memory cards; and otherstorage media. As used herein, a storage device is a device that allowsfor reading and/or writing to a storage medium. Storage devices include,hard disk drives, DVD drives, flash memory devices, and others. Thesoftware that when executed implements the invention may be stored inRAM or other memory on server 120. The software that when executedimplements the invention may also be obtained from another servercomputer or computing device locally or remotely accessible, such as,for example, over a network such as network 140, via a directconnection, and otherwise.

The network 140 may include or be one or more of a local area network(LAN), a wide area network (WAN), a storage area network (SAN), or acombination of these. The network 140 may be wired, wireless, or acombination of these, and may include or be augmented by satellitecommunications. The network 140 may include or be the Internet. Thenetwork 140 may be public or private, or a combination of public andprivate. The network 140 may be comprised of numerous nodes providingnumerous physical and logical paths for data to travel. The network 140may support one or more well known, proprietary, and othercommunications protocols, including, for example, lower level protocolssuch as Ethernet; higher level protocols such as the hyper-text transferprotocol (HTTP); transport layer protocols such as the User DatagramProtocol (UDP), the Transmission Control Protocol (TCP), and theInternet Protocol (IP); and others.

FIG. 2 is a block diagram of a second environment in accordance with theinvention. In one implementation, the environment may include a clientcomputer 210 that establishes a dial-up connection with a NAP. Toachieve this dial-up connection, a connection 216 is established with atelephone company (telco) 220. A switch 224, gateway or other device atthe telephone company may communicate with a Remote AuthenticationDial-In User Service (RADIUS) server 228 to authenticate thesubscription of the user of the client computer 210 with the NAP. A useror subscriber identifier may be passed to the RADIUS server 228. TheRADIUS protocol and software may be used for authentication andaccounting of dial-up subscribers. The telephone company 220 and/or theswitch 224 may include or be a RADIUS client and may include or be aNetwork Access Server (NAS).

After the RADIUS server authenticates that the user of the clientcomputer 210 is a registered subscriber, the switch 224, gateway orother device at the telephone company 220 may communicate with anapplication server 226 to obtain a token and to learn the level ofservice that is to be provided to the subscriber. The token may be auniquely computed data item computed to ensure secure use of NAPservices. In addition to the token, when the level of service is of acertain level that includes acceleration, the application server 226 mayalso pass a proxy server address to the subscriber at the clientcomputer 210 through the switch 224. The 210 client computer then passesthe token and the subscriber identifier to the proxy server 230designated by the proxy server address provided by the applicationserver 226. It is through the proxy server 230 that the subscriber atthe client computer 210 gains accelerated access to the network 250 anddevices 260.

The proxy server 230 may include software which achieves the methodsdescribed herein. The proxy server 230 may be coupled with a cacheserver 240. The cache server 240 is coupled to a network 250, such asthe Internet. It is by communicating through the telephone company 220,the proxy server 230 and the cache server 240 that the client computermay access information available from devices 260 via the network 250.In some circumstances information requested by a NAP subscriber atclient computer 210 may be available and served by local or remote cacheserver 240, or may be available in a cache included in the proxy server230 and served by the proxy server. In other circumstances, theinformation requested by a NAP subscriber at client computer 210 may berequested from a device 260 via network 250. One or more of the devices260 may be an origin server as defined below.

Software Architecture

FIG. 3 is a block diagram of a software architecture in accordance withthe invention. The client computer 310 may be a computing device and mayhave an operating system 320 such as, for example, variations of theLinux, Unix, MS-DOS, Microsoft Windows, Palm OS, and Apple Mac OSoperating systems. The operating system may include networkcommunications software 322. The network communications software 322 issoftware that allows for communicating over a network. The networkcommunications software 322 may provide support for communicationsaccording to protocols such as UDP, TCP, IP, and others.

The client computer 310 may include: an Internet web browser 312 such asNetscape Navigator, Microsoft Internet Explorer, Opera, and others; anNAP client program 314 such as that provided by NetZero, Juno and otherNAPs; and application programs 316 such as word processors,spreadsheets, games, and others. The NAP client program 314 may have aweb browser or similar software incorporated therein or integratedtherewith. The NAP client program 314 may include a header optimizerclient software module, plug-in or other software (not shown). The NAPclient program 314 and/or the web browser 312 may provide support forHTTP and other higher level communications protocols. In one embodiment,the web browser 312 accesses a network such as network 360 through NAPclient program 314.

A subscriber may use the NAP client program 314 to establish aconnection 350 with a server computer 330. To achieve connection 350,the NAP client program 314 may establish a dial-up phone lineconnection, a DSL connection, a cable modem connection, and others, witha server computer 330. The NAP client 314 may support the Point-to-PointProtocol (PPP), and may also support the Password AuthenticationProtocol (PAP) or the Challenge-Handshake Authentication Protocol(CHAP).

When establishing the connection 350 with the server computer 330, theNAP client program 314 may provide subscriber information and NAP clientprogram information to the NAP server program 334. The NAP clientprogram information may include a version number of the NAP clientprogram 314, and the subscriber information may include a subscriberidentifier, subscriber profile information, and/or a subscriber level ofservice. Alternatively, the subscriber information may be solely asubscriber identifier, and the NAP server program 334 may accesssubscriber profile information, subscriber level of service, and/orother subscriber information from a NAP database (not shown) on oraccessible by the server computer 330.

The NAP may provide multiple servers, proxy servers and cache serverswhich are accessed by subscribers based on the level of service thesubscriber purchases. When the connection 350 is established, the NAPclient program 314 may receive a server designation from the NAP serverprogram 334 based on the level of service of the subscriber. The serverdesignation may be the proxy server address described above with regardto FIG. 2. The NAP server program 334 may provide services to the NAPsubscriber based on a level of service. The level of service maydetermine whether the acceleration techniques described herein andimplemented via the header optimizer 332 should be invoked for thesubscriber. The acceleration techniques may be made accessible to allsubscribers, to subscribers having a NAP client program having aparticular version number, and/or only to those subscribers paying for aparticular level of service that includes accelerated communications.

When accelerated communications are to be provided, the NAP serverprogram 334 may provide a proxy server address or other server address,such as a local host address, to the NAP client program 314. The NAPserver program 334 may also provide a local proxy port to the NAP clientprogram 314. In one embodiment, the NAP client program 314 sets a proxyaddress of the web browser 312 to be the local host address andspecifies a local proxy port as provided by the NAP server program 334.The web browser 312 may then use the NAP Client program 334 to accessthe Internet and/or other network. In another embodiment, a subscriberusing the web browser 312 communicates with and over the network 360 viathe NAP client program 314. In this embodiment, the NAP client program314 directs network communications to a server computer which isdesignated by the proxy address. Other proxy configurations are alsocontemplated.

The server computer 330 may be a server computer as known in the art,and may be a group, cluster or LAN of server computers which may beaugmented with routers, gateways, switches and other network devices.The server computer may be the server computer 120 of FIG. 1, the proxyserver 230 of FIG. 2, or may include both the proxy server 230 and thecache server 240 of FIG. 2. The server computer 330 may include anoperating system such as, for example, variations of the Linux, Unix,Microsoft Windows, and Apple MAC OS operating systems. The operatingsystem may include network communications software 342 that allows forcommunication over a network. The network communications software 342may provide support for communications according to protocols such asUDP, TCP, IP, and others. The network communications software 342 mayprovide support for wired and/or wireless network communications.

The server computer 330 may include NAP server program 334 which is usedto serve communications with the NAP client program 314 on clientcomputer 310. The NAP server program 334 may provide support for HTTPand other higher level communications protocols. The methods describedherein may be implemented as software referred to as header optimizersoftware 332. The header optimizer software 332 may be included in theNAP server program 334, may be a plug-in to the header optimizersoftware 332, and may execute on the server computer 330.

The server computer 330 prepares responses to requests received from theweb browser 312 and/or the NAP client program 314 on client computer310. The NAP server program 334 may receive requests from clientcomputer 310. In response to a request, the server computer 330 mayfulfill the request by referring to local data, may fulfill the requestby referring to a cache server (not shown), or may forward the requestto a server on network 360. The cache server may be a server known inthe art, may be like the cache server 240 of FIG. 2, and may be local orremote to the server computer 330.

With regard to FIGS. 1, 2 and 3 and the discussion thereof, additionaland fewer units, modules or other arrangement of software, hardware anddata may be used to achieve the invention described herein.

Methods

FIG. 4 is a flow chart of a method in accordance with the invention. Aclient request is received, as shown in block 410. The request may be anHTTP GET method. The request may specify a resource. The resource may beidentified in various ways, such as, for example, by a Uniform ResourceIdentifier (URI), which may be a Uniform resource Locator (URL). Theresource may be a file and may be a single object. The resource may be afile containing a list of multiple objects. An object may be a singlegraphics file such as, for example, a Graphics Interchange Format (GIF)or Joint Photographic Experts Group (JPEG) file. There may also be otherkinds of objects, including, but not limited to, audio, video,multimedia, and others. Pertinent information from the client requestmay be stored for further use and/or analysis, as shown in block 412.The client request may be forwarded to a server, and the server may bean origin server, cache server or other kind of server, as shown inblock 414. An origin server is a server that hosts the original versionof the resource or object specified in the request. The origin servermay be specified as part of the URI.

A response is received form the origin server, the cache server or otherserver, as shown in block 416. A check may be made to determine whetherthe response includes an expiration, as shown in block 420. Thisexpiration may be referred to as a native expiration, as it is anexpiration that was included in the response by the origin server. Thischeck may be made by examining the “Expires” field of the response whenthe response conforms to the HTTP protocol. If the response includes anexpiration, no changes are made to the response, and the response isforwarded to the client, as shown in block 450.

If the response does not include an expiration, a check is made todetermine whether the response is an appropriate type, as shown in block430. In one embodiment, the acceleration methods by header modificationdescribed herein are used only with those types of files included in anappropriate type list. A response is an appropriate type when it is orincludes an object or one or more objects that is/are in the appropriatetype list or group. The appropriate type list or group may includevarious types of files and objects, and, in particular, any files orobjects referenced in a web page or other file. The web page may becontrolled by a Hyper-Text Markup Language (HTML) file or other kind offile. The appropriate type list or group may include various types offiles and objects referenced in an HTML or other file, includingMultipurpose Internet Mail Extensions (MIME) file types. The appropriatetype list may include graphic files such as JPEG and GIF files, portabledocument format (PDF) files and postscript files. The appropriate typelist may include multimedia files such as HTML files, Windows MediaFiles, Moving Pictures Experts Group (MPEG) files, RealMedia files,QuickTime files, Flash files, as well as executable programs, JavaScriptfiles, Cascading Style Sheet (CSS) files, and others.

In another embodiment, the acceleration methods by header modificationdescribed herein are used when certain characteristics of the files ortransactions requested conform to system defined specifications such asfile size, file creation date, file creation program, specified URI,specified server, and others.

If the response is an appropriate type, an expiration for the responsemay be computed, as shown in block 442. The computed expiration may beinserted in the response, creating an amended response, as shown inblock 444. The expiration may be inserted as an “Expires” header whenthe response is an HTTP response. As such, the methods described hereinmay be referred to as header injection. The amended response may beforwarded to the client, as shown in block 446. The amended response maybe forwarded in place of the response received from the origin server.

In conjunction with this method, a copy of the response, the amendedresponse, and/or the objects contained in the response may be stored orcached for future use. This may occur, for example, after or inconjunction with blocks 436 and 440. The caching or storing may occur ata server, such as a local or remote proxy server or cache server. Thestoring or caching may be to a volatile and/or non-volatile storagemedium (e.g., RAM, hard disk) coupled with the server. In this way, whenother subscribers/clients request the object, the stored or cachedobject may be provided to the client without having to forward therequest to the origin server. This storing/caching reduces the numberrequests that are made to origin servers, reduces the processing andnetwork communications overhead associated with forwarding requests, andcauses the network communications to accelerate.

When a client receives the response, the response and/or the object orobjects in the response may be cached or otherwise stored by the webbrowser or otherwise by the client for later use. The web browser of theclient may manage its own cache and store responses and/or the object orobjects received in a response. Typically, when a web page is specifiedby a subscriber, a client web browser will check to see if an objectincluded in the specified web page is in its cache, and, if so, whetherit has expired before requesting the object or the web page from aserver.

When a subscriber specifies a web page, the web page is comprised ofnumerous objects. Each graphic on a web page may be a separate object.When a server serves objects that are lacking an expiration, thesubscriber's web browser must always request the object from the server,even though the object has not changed on the server, or on the originserver. This causes the server to process the request and return an“OK”, “not modified” or similar response to the client. This causes theclient to create and make the request, and then process the response. Inthese cases, responses and objects that do not have an expiration causeprocessing resources to be needlessly expended both on the client and onthe server, and cause needless messages to be exchanged between theclient and the server.

The methods described herein explain how a server may add an expirationto objects received from a server such as, for example, an originserver. A NAP server may provide the amended response to a client inplace of an original response. As such, when the client attempts at alater time to access the object that was included in the response, theweb browser retrieves the object from a cache associated with the webbrowser on the client machine. Adding an expiration to an object reducesthe number of unneeded requests made by the client to the server. Thereduced number of requests generated by clients is magnified by thenumber of subscribers that are serviced by a particular server or NAPserver. The server or NAP server, therefore, expends less processingtime, effort and resources in handling unnecessary requests fromclients.

The methods described herein improve the throughput directly at theclient by causing the client to avoid having to make requests forobjects which are not stale or old. The methods described hereinaccelerate network communications by increasing the throughput ofnetwork communications to the subscriber by both reducing the number ofneedless requests made by the client of the server, and by increasingthe throughput of information through the server by reducing the amountof needless processing performed by the server in handling requests forfresh objects, that is, objects that have not changed on the originserver.

FIG. 5 is a flow chart of a second method in accordance with theinvention. A client request is received, as shown in block 510. If therequest header includes a modification query, pertinent information fromthe modification query such as, for example, a date, an object type andthe URI contained in the request, may be stored for later use as requesthistory data, as shown in block 512. When the request is an HTTPrequest, the modification query may be an “if-modified-since” requestheader field.

A data structure such as a hash table may be used to store requesthistory information such as a request time (obtained from the request),and a current time (the time of receiving the request). Each request maybe assigned a request sequence number which may be a number that isincremented for each received request. The request history data may alsoinclude other time related data found in a request and/or a response,including modification query data such as an “if-modified-since” valueincluded in a request, modification history data such as a“last-modified” value included in a response, the “time-to-live” valuecomputed as described below, an expiration, either included in aresponse or calculated, and others. The request history data may beindexed and/or accessed by the request sequence number, or by otherinformation stored as request history data.

The server may check to see if the client request may be serviced byreferring to a local server cache, by referring to a local or remotecache server, or by referring to a local or remote proxy server. If therequest cannot be handled by referring to a local cache, a cache server(local or remote) or a proxy server (remote or local), the request maybe forwarded to the origin server, as shown in block 514.

The server may receive a response from the origin server, as shown inblock 516, and may check whether the response includes an actionablestatus code, as shown in block 520. An actionable status code is aresponse that is included in an actionable status code list or groupmaintained by the server. The actionable status code list may signifyOK, not modified, no changes made, and others. When using HTTP, theactionable status codes may include status codes 200 signifying “OK” and304 signifying “not modified.”

If the status code is actionable, a check may be made to determinewhether the response includes an expiration, as shown in block 522. Thisanalysis may be similar to that regarding block 420 of FIG. 4. If theresponse does not include an expiration, the response may be reviewed todetermine the content type, or the content type may be retrieved fromthe response, as shown in block 530. When the response is an HTTPresponse, the “content-type” header may be examined to learn the type ofobject or objects included in the response.

A check may be made to determine whether a response is an appropriatetype or if the object in the response is an appropriate type, as shownin block 532. This analysis may be similar to that regarding block 430of FIG. 4. If the response is an appropriate type, a time-to-live forthe response may be determined, as shown in block 540. The time-to-livemay be calculated as described below with regard to FIG. 6. Anexpiration of the response may be calculated based on the time-to-live,as shown in block 542. The calculated expiration may be inserted intothe response, creating an amended response, as shown in block 544. Whenthe response is an HTTP response, the expiration may be added to theHTTP header of the response in the “Expires” field. The amended responsemay be forwarded to the client, as shown in block 546.

If the status code is not actionable, as shown in block 520; or if theresponse includes an expiration, as shown in block 522; or if theresponse if not an appropriate type as shown in block 532; the responseis forwarded to the client without modification, as shown in block 550.

FIG. 6 is a flow chart of a method to compute the expiration of aresponse in accordance with the invention. The method describedregarding FIG. 6 may replace blocks 540, 542 and 544 of FIG. 5. Themethod shown in FIG. 6 may be used to determine the time-to-live for aresponse and the expiration based thereon. A check may be made todetermine whether the response includes modification history data, asshown in block 610. The modification history data may be a date and timewhen the object in the response was last modified. For example, when theresponse is an HTTP response the modification history data may be a“last-modified” header. The method may also be used with other kinds ofresponses having similar modification data in headers, fields, orsimilar information in the response.

If the response includes modification history data such as alast-modified header, the time-to-live (TTL) for the response may bemade based on an age factor, the current time (T) and the last-modifiedvalue (LM), as shown in block 620. The age factor may be a numberbetween 0 and 1, and/or may be a value determined to best optimize theresults of the method. The age factor (AF) may be 0.08, 0.1, 0.25, 0.3,0.8, and others. The computation described in block 620 may be computedaccording to the formula: TTL=AF×(T−LM).

A check may be made to determine whether the computed time-to-live isgreater than a system defined maximum time-to-live, as shown in block622. The system defined maximum time-to-live may be a constant that isfound best to achieve the goals of the method. The system definedmaximum time-to-live may be from a fraction of one day to fifty days, ormore, and may be expressed in seconds, minutes, days, weeks, or months(e.g., 432,000 seconds, five days). If the time-to-live is greater thanthe system defined maximum time-to-live, the time-to-live may be set tobe the system defined maximum time-to-live, as shown in block 624. Theflow of actions then continues at block 630.

If the computed time-to-live is not greater than the system definedmaximum time-to-live, a check may be made to determine whether thetime-to-live is less than a system defined minimum time-to-live, asshown in block 626. The minimum time-to-live may be defined as a timesuch as, for example, two minutes, five minutes, twenty minutes, andothers. The system defined minimum time-to-live may be a constant thatis found best to achieve the goals of the method. If the computedtime-to-live is not less than a system defined minimum time-to-live, theflow of actions continues at block 630.

At block 630, the expiration header is set to be the time-to-live plusthe current time. The expiration header may be inserted or added to theresponse, creating an amended response, as shown in block 632.

If the computed time-to-live is less than a system defined minimumtime-to-live, the response is not amended, as shown in block 660.

Returning to a discussion of block 610, if the response does not includemodification history data such as a “last-modified” header, the statuscode included in the response is checked to determine if it isproscribed from further processing, as shown in block 640. This may beachieved by referring to a proscribed status code list stored on theserver. The proscribed status code list may include the status code“OK”. If the response status code is not proscribed, then an attempt ismade to retrieve a modification query value from a stored or cached datastructure, such as the request history hash table discussed above, basedon the URI or other resource identifier and the response type includedin the response, as shown in block 642. The modification query data maybe an “if-modified-since” value as defined in the HTTP protocol. Similarheaders or fields may be used to achieve the same result in otherprotocols, be they public, proprietary or other.

If the URI or other resource identifier and response type successfullyretrieve a modification query value such as an “if-modified-since” (IMS)value, as shown in block 644, the time-to-live for the response iscomputed based on the age factor, the current time and the modificationquery value, as shown in block 650. The time-to-live may be computedaccording to the following formula: TTL=AF×(T−IMS). That is, when no“last modified” field or other modification history data is present in aresponse, a stored “if-modified-since” value or other modification queryvalue that corresponds to the same URI or other resource identifier andobject/response type may be used in its place. The flow of actions thencontinues at block 622, as set forth above.

If the response status code is proscribed, such as, for example, an OKsuch as code number 200 of the HTTP standard, or a similar proscribedresponse code, or if the URI or other resource identifier and responsetype cannot be found in the request history hash table or other storedor cached data structure, the response is not amended, as shown in block660.

The time-to-live computation may also be made based on variouscircumstances and factors, such as, for example, the type of the object,the source URI of the object, the program that created the object, thesize of the object, and others. The time-to-live computation in blocks620 and 650 may also be based on the source URI or other resourceidentifier in the response. A check may be made to look up an age factorassociated with a particular URI or other resource identifier.Similarly, an age factor may be used that corresponds to a particularresponse type or object type. In this way responses from websites mayexpire earlier or later as reflected in the age factor. Responsesincluding certain kinds of objects may expire earlier or later asreflected in the age factor. Further, traffic analysis may be performedsuch that a server evaluates traffic patterns to discern which sizes,kinds, and types of files and specific files, as well as the sources andpopularity of specific files are best suited for the header injectiontechnique described herein. This traffic analysis and the resultsthereof may be used in addition to or in place of the computations usinglast-modified-since and if-modified-since as described herein.

With regard to blocks 622, 624 and 626, the maximum time-to-live and/orthe minimum time-to-live may each be a system defined constant. Tocontour the method to further improve throughput, the maximumtime-to-live and/or the minimum time-to-live may each be constants thatare set for particular kinds of responses or kinds of objects. That is,the maximum time-to-live and/or the minimum time-to-live may each varydepending on whether the type of object is a graphic, is a video clip,is a PDF file, and others. In addition, the maximum time-to-live and/orthe minimum time-to-live may each depend on a URI or other resourceidentifier. In this way, for example, website servers that are known toserve news or other timely information may have a maximum time-to-liveshorter or smaller than other website servers. The maximum time-to-liveand/or the minimum time-to-live may each depend on one, either, orneither of the type of object and the URI or other resource identifierspecified.

With regard to FIGS. 4, 5 and 6, additional and fewer steps may betaken, steps may be added or removed, and the steps as shown may becombined or further refined to achieve the methods described herein. Inaddition, the steps taken may be organized in an order other than asshown and described herein.

Although exemplary embodiments of the present invention have been shownand described, it will be apparent to those having ordinary skill in theart that a number of changes, modifications, or alterations to theinvention as described herein may be made, none of which depart from thespirit of the present invention. All such changes, modifications andalterations should therefore be seen as within the scope of the presentinvention.

1. A method for increasing the throughput of network communicationsperformed by a network access provider server, the method comprising:the network access provider server establishing a connection with aclient computer the network access provider server receiving a requestfor a requested object from a requester, wherein the requester is a webbrowser on the client computer the network access provider serverforwarding the request to a server the network access provider serverreceiving a response from the server the network access provider serverreviewing the response to determine whether the response includes anative expiration when the response does not include the nativeexpiration the network access provider server computing a computedexpiration for the response the network access provider server insertingthe computed expiration into the response creating an amended responsethe network access provider server forwarding the amended response tothe requester, wherein the amended response includes the requestedobject storing the amended response the network access provider serverproviding the amended response to other requesters at other clientcomputers that request the requested object, the providing achievedwithout additional communication with the server when the responseincludes the native expiration, the network access provider serverforwarding the response to the requester.
 2. The method of claim 1wherein the server comprises an origin server.
 3. The method of claim 1wherein the computed expiration is based on at least one of a responsecontent type and a response resource identifier.
 4. The method of claim1 wherein the computed expiration is based on a time-to-live.
 5. Themethod of claim 1 further comprising the network access provider serverevaluating whether a content type of the response is appropriate thenetwork access provider server performing the reviewing only when thecontent type of the response is appropriate.
 6. The method of claim 1wherein the network access provider server evaluating whether a contenttype of the response is appropriate comprises the network accessprovider server checking to determine whether the content type is in anappropriate type list.
 7. The method of claim 1 wherein the appropriatetype list comprises at least one of graphic, JavaScript, Cascading StyleSheet, portable document format (PDF), executable program, audio, video,and multimedia.
 8. The method of claim 1 wherein the network accessprovider server receiving a request comprises the network accessprovider server storing request information as request history data. 9.The method of claim 1 wherein the request information includes a requestresource identifier, a request content type, and a modification querywhen the modification query is present.
 10. The method of claim 1wherein the network access provider server computing the computedexpiration comprises: the network access provider server evaluatingwhether the response includes a modification history when the responseincludes the modification history, the network access provider servercomputing a time-to-live for the response based on an age factor, acurrent time and a value of the modification history the network accessprovider server computing the computed expiration based on the currenttime and the time-to-live when the response does not include themodification history, the network access provider server retrieving amodification query value from the request history data based on aresponse type and a response location when the modification query valueis retrieved, the network access provider server computing thetime-to-live for the response based on an age factor, a current time andthe modification query value, the network access provider servercomputing the computed expiration based on the current time and thetime-to-live when the retrieving the modification query value is notsuccessful, the network access provider server forwarding the responseto the requester.
 11. The method of claim 1 further comprising: when thetime-to-live is greater than a defined maximum, the network accessprovider server setting the time-to-live to be the defined maximum whenthe time-to-live is less than a defined minimum, forwarding the responseto the requester.
 12. The method of claim 1 wherein the request is ahyper-text transfer protocol (HTTP) get, the modification query value isan HTTP if-modified-since value, and the modification history value isan HTTP last-modified value.
 13. A storage medium having instructionsstored thereon which when executed by a processor cause a network accessprovider server to perform operations comprising: the network accessprovider server establishing a connection with a client computer thenetwork access provider server receiving a request for a requestedobject from a requester, wherein the requester is a web browser on theclient computer the network access provider server forwarding therequest to a server the network access provider server receiving aresponse from the server the network access provider server reviewingthe response to determine whether the response includes a nativeexpiration when the response does not include the native expiration thenetwork access provider server computing a computed expiration for theresponse the network access provider server inserting the computedexpiration into the response creating an amended response the networkaccess provider server forwarding the amended response to the requester,wherein the amended response includes the requested object the networkaccess provider server storing the amended response the network accessprovider server providing the amended response to other requesters onother client computers that request the requested object, the providingachieved without additional communication with the server when theresponse includes the native expiration, the network access providerserver forwarding the response to the requester.
 14. The storage mediumof claim 1 wherein the server comprises an origin server.
 15. Thestorage medium of claim 1 having further instructions stored thereonwhich when executed by the processor cause the network access providerserver to perform further operations comprising: the network accessprovider server evaluating whether a content type of the response isappropriate the network access provider server performing the reviewingonly when the content type of the response is appropriate.
 16. Thestorage medium of claim 1 wherein the network access provider serverevaluating whether a content type of the response is appropriatecomprises the network access provider server checking to determinewhether the content type is in an appropriate type list.
 17. The storagemedium of claim 1 wherein the appropriate type list comprises at leastone of graphic, JavaScript, Cascading Style Sheet, portable documentformat (PDF), audio, video, and multimedia.
 18. The storage medium ofclaim 1 wherein the computed expiration is based on at least one of aresponse content type and a response resource identifier.
 19. Thestorage medium of claim 1 wherein the computed expiration is based on atime-to-live.
 20. The storage medium of claim 1 wherein the networkaccess provider server receiving a request comprises the network accessprovider server storing request information as request history data. 21.The storage medium of claim 1 wherein the request information includes arequest resource identifier, a request content type, and a modificationquery when the modification query is present.
 22. The storage medium ofclaim 1 wherein the network access provider server computing thecomputed expiration comprises: the network access provider serverevaluating whether the response includes a modification history when theresponse includes the modification history, the network access providerserver computing a time-to-live for the response based on an age factor,a current time and a value of the modification history the networkaccess provider server computing the computed expiration based on thecurrent time and the time-to-live when the response does not include themodification history, the network access provider server retrieving amodification query value from the request history data based on aresponse type and a response location when the modification query valueis retrieved, the network access provider server computing thetime-to-live for the response based on an age factor, a current time andthe modification query value, the network access provider servercomputing the computed expiration based on the current time and thetime-to-live when the retrieving the modification query value is notsuccessful, the network access provider server forwarding the responseto the requester.
 23. The storage medium of claim 1 having furtherinstructions stored thereon which when executed by the processor causethe network access provider server to perform operations furthercomprising: when the time-to-live is greater than a defined maximum, thenetwork access provider server setting the time-to-live to be thedefined maximum when the time-to-live is less than a defined minimum,the network access provider server forwarding the response to therequester.
 24. The storage medium of claim 1 wherein the request is ahyper-text transfer protocol (HTTP) get, the modification query value isan HTTP if-modified-since value, and the modification history value isan HTTP last-modified value.
 25. A network access provider serverconfigured to accelerate network traffic delivery, the network accessprovider server comprising: a processor a memory coupled with theprocessor a storage medium having instructions stored thereon which whenexecuted cause the network access provider server to perform actionscomprising the network access provider server establishing a connectionwith a client computer receiving a request for a requested object from arequester, wherein the requester is a web browser on the client computerforwarding the request to a server receiving a response from the serverreviewing the response to determine whether the response includes anative expiration when the response does not include the nativeexpiration computing a computed expiration for the response insertingthe computed expiration into the response creating an amended responseforwarding the amended response to the requester, wherein the amendedresponse includes the requested object storing the amended responseproviding the amended response to other requesters on other clientcomputers that request the requested object, the providing achievedwithout additional communication with the server when the responseincludes the native expiration, forwarding the response to therequester.
 26. The network access provider server of claim 1 wherein theserver comprises an origin server.
 27. The network access providerserver of claim 1 having further instructions which when executed causethe processor to perform further operations comprising: evaluatingwhether a content type of the response is appropriate performing thereviewing only when the content type of the response is appropriate. 28.The network access provider server of claim 1 wherein the evaluatingwhether a content type of the response is appropriate comprises checkingto determine whether the content type is in an appropriate type list.29. The network access provider server of claim 1 wherein theappropriate type list comprises at least one of graphic, JavaScript,Cascading Style Sheet, portable document format (PDF), audio, video, andmultimedia.
 30. The network access provider server of claim 1 whereinthe computed expiration is based on at least one of a response contenttype and a response resource identifier.
 31. The network access providerserver of claim 1 wherein the computed expiration is based on atime-to-live.
 32. The network access provider server of claim 1 whereinthe receiving a request comprises storing request information as requesthistory data.
 33. The network access provider server of claim 1 whereinthe request information includes a request resource identifier, arequest content type, and a modification query when the modificationquery is present.
 34. The network access provider server of claim 1wherein the computing the computed expiration comprises: evaluatingwhether the response includes a modification history when the responseincludes the modification history, computing a time-to-live for theresponse based on an age factor, a current time and a value of themodification history computing the computed expiration based on thecurrent time and the time-to-live when the response does not include themodification history, retrieving a modification query value from therequest history data based on a response type and a response locationwhen the modification query value is retrieved, computing thetime-to-live for the response based on an age factor, a current time andthe modification query value, computing the computed expiration based onthe current time and the time-to-live when the retrieving themodification query value is not successful, forwarding the response tothe requester.
 35. The network access provider server of claim 1 whereinthe storage medium has further instructions stored thereon which whenexecuted cause the to perform further operations comprising: when thetime-to-live is greater than a defined maximum, setting the time-to-liveto be the defined maximum when the time-to-live is less than a definedminimum, forwarding the response to the requester.
 36. The networkaccess provider server of claim 1 wherein the request is a hyper-texttransfer protocol (HTTP) get, the modification query value is an HTTPif-modified-since value, and the modification history value is an HTTPlast-modified value.